/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
 * Copyright (C) 2020 M. Straver. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "HRTFDatabaseLoader.h"
#include "HRTFDatabase.h"

using namespace mozilla;

namespace WebCore {

// Singleton
nsTHashtable<HRTFDatabaseLoader::LoaderByRateEntry>*
    HRTFDatabaseLoader::s_loaderMap = nullptr;

size_t HRTFDatabaseLoader::sizeOfLoaders(mozilla::MallocSizeOf aMallocSizeOf)
{
    return s_loaderMap ? s_loaderMap->SizeOfIncludingThis(aMallocSizeOf) : 0;
}

already_AddRefed<HRTFDatabaseLoader> HRTFDatabaseLoader::createAndLoadAsynchronouslyIfNecessary(float sampleRate)
{
    MOZ_ASSERT(NS_IsMainThread());

    RefPtr<HRTFDatabaseLoader> loader;
    
    if (!s_loaderMap) {
        s_loaderMap = new nsTHashtable<LoaderByRateEntry>();
    }

    LoaderByRateEntry* entry = s_loaderMap->PutEntry(sampleRate);
    loader = entry->mLoader;
    if (loader) { // existing entry
        MOZ_ASSERT(sampleRate == loader->databaseSampleRate());
        return loader.forget();
    }

    loader = new HRTFDatabaseLoader(sampleRate);
    entry->mLoader = loader;

    loader->loadAsynchronously();

    return loader.forget();
}

HRTFDatabaseLoader::HRTFDatabaseLoader(float sampleRate)
    : m_refCnt(0)
    , m_threadLock("HRTFDatabaseLoader")
    , m_databaseLoaderThread(nullptr)
    , m_databaseSampleRate(sampleRate)
    , m_databaseLoaded(false)
{
    MOZ_ASSERT(NS_IsMainThread());
}

HRTFDatabaseLoader::~HRTFDatabaseLoader()
{
    MOZ_ASSERT(NS_IsMainThread());

    waitForLoaderThreadCompletion();
    m_hrtfDatabase.reset();

    if (s_loaderMap) {
        // Remove ourself from the map.
        s_loaderMap->RemoveEntry(m_databaseSampleRate);
        if (s_loaderMap->Count() == 0) {
            delete s_loaderMap;
            s_loaderMap = nullptr;
        }
    }
}

size_t HRTFDatabaseLoader::sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
{
    size_t amount = aMallocSizeOf(this);

    // NB: Need to make sure we're not competing with the loader thread.
    const_cast<HRTFDatabaseLoader*>(this)->waitForLoaderThreadCompletion();

    if (m_hrtfDatabase) {
        amount += m_hrtfDatabase->sizeOfIncludingThis(aMallocSizeOf);
    }

    return amount;
}

class HRTFDatabaseLoader::ProxyReleaseEvent final : public Runnable {
public:
    explicit ProxyReleaseEvent(HRTFDatabaseLoader* loader) : mLoader(loader) {}
    NS_IMETHOD Run() override
    {
        mLoader->MainThreadRelease();
        return NS_OK;
    }
private:
    HRTFDatabaseLoader* mLoader;
};

void HRTFDatabaseLoader::ProxyRelease()
{
    nsCOMPtr<nsIThread> mainThread = do_GetMainThread();
    if (MOZ_LIKELY(mainThread)) {
        RefPtr<ProxyReleaseEvent> event = new ProxyReleaseEvent(this);
        DebugOnly<nsresult> rv =
            mainThread->Dispatch(event, NS_DISPATCH_NORMAL);
        MOZ_ASSERT(NS_SUCCEEDED(rv), "Failed to dispatch release event");
    } else {
        // Should be in XPCOM shutdown.
        MOZ_ASSERT(NS_IsMainThread(),
                   "Main thread is not available for dispatch.");
        MainThreadRelease();
    }
}

void HRTFDatabaseLoader::MainThreadRelease()
{
    MOZ_ASSERT(NS_IsMainThread());
    int count = --m_refCnt;
    MOZ_ASSERT(count >= 0, "extra release");
    NS_LOG_RELEASE(this, count, "HRTFDatabaseLoader");
    if (count == 0) {
        // It is safe to delete here as the first reference can only be added
        // on this (main) thread.
        delete this;
    }
}

// Asynchronously load the database in this thread.
static void databaseLoaderEntry(void* threadData)
{
    PR_SetCurrentThreadName("HRTFDatabaseLdr");

    HRTFDatabaseLoader* loader = reinterpret_cast<HRTFDatabaseLoader*>(threadData);
    MOZ_ASSERT(loader);
    loader->load();
}

void HRTFDatabaseLoader::load()
{
    MOZ_ASSERT(!NS_IsMainThread());
    MOZ_ASSERT(!m_hrtfDatabase.get(), "Called twice");
    // Load the default HRTF database.
    m_hrtfDatabase = HRTFDatabase::create(m_databaseSampleRate);
    m_databaseLoaded = true;
    // Notifies the main thread of completion.  See loadAsynchronously().
    Release();
}

void HRTFDatabaseLoader::loadAsynchronously()
{
    MOZ_ASSERT(NS_IsMainThread());
    MOZ_ASSERT(m_refCnt, "Must not be called before a reference is added");

    // Add a reference so that the destructor won't run and wait for the
    // loader thread, until load() has completed.
    AddRef();

    MutexAutoLock locker(m_threadLock);
    
    MOZ_ASSERT(!m_hrtfDatabase.get() && !m_databaseLoaderThread,
               "Called twice");
    // Start the asynchronous database loading process.
    m_databaseLoaderThread =
        PR_CreateThread(PR_USER_THREAD, databaseLoaderEntry, this,
                        PR_PRIORITY_NORMAL, PR_GLOBAL_THREAD,
                        PR_JOINABLE_THREAD, 0);
}

bool HRTFDatabaseLoader::isLoaded() const
{
    return m_hrtfDatabase.get();
}

void HRTFDatabaseLoader::waitForLoaderThreadCompletion()
{
    MutexAutoLock locker(m_threadLock);
    
    // waitForThreadCompletion() should not be called twice for the same thread.
    if (m_databaseLoaderThread) {
        DebugOnly<PRStatus> status = PR_JoinThread(m_databaseLoaderThread);
        MOZ_ASSERT(status == PR_SUCCESS, "PR_JoinThread failed");
    }
    m_databaseLoaderThread = nullptr;
}

void HRTFDatabaseLoader::shutdown()
{
    MOZ_ASSERT(NS_IsMainThread());
    if (s_loaderMap) {
        // Set s_loaderMap to nullptr so that the hashtable is not modified on
        // reference release during enumeration.
        nsTHashtable<LoaderByRateEntry>* loaderMap = s_loaderMap;
        s_loaderMap = nullptr;
        for (auto iter = loaderMap->Iter(); !iter.Done(); iter.Next()) {
          iter.Get()->mLoader->waitForLoaderThreadCompletion();
        }
        delete loaderMap;
    }
}

} // namespace WebCore
